This study is being conducted as part of the National Cooperative Study of Drugs and Coronary Heart Disease. The primary objective of the study is to test the efficacy of several drugs in the long term therapy of Coronary Heart Disease in men aged 30 to 64 with evidence of previous myocardial infarction. To achieve this end, and assessment is to be made of the ability of these drugs to be evaluated on such other end-points as recurrent myocardial infaction, acute coronary insufficiency, angina pectoris, congestive heart failure, cerebrovascular and peripheral vascular disease. The study has the additional purpose of evaluating the relationship (if any) between drug effects on serum cholesterol levels and on morbidity-mortality rates. All the drugs proposed for evaluation have been reported to influence serum cholesterol-lipidlipoprotein levels. Since lipid concentrations and atherosclerotic disease occurrence rates have been shown to be closely associated it is resonable to hypothesize that drugs lowering lipid levels may have a beneficial effect on atherosclerotic coronary heart disease. The aim of the study is to determine whether any of the drugs can reduce the mortality or recurrent myocardial infarction by 25% or more. If one or more drugs should be successful, the implications are obvious.